Ten More Common Myths of Cold Water Swimming

Following the previous Ten Common Myths of Cold Water Swimming. There are quite a few myths, most probably better described as misunderstandings, about cold water and cold water swimming. A few are even true.

  • 11. Fresh water feels colder than sea water at the same temperature.

    Ice at the edges of Lough Dan,scene of Fergal Somerville's Ice Mile Invitationals

    Ice at the edges of Lough Dan,scene of Fergal Somerville’s Ice Mile Invitationals

This myth is usually confirmed by most experienced cold water swimmers. Most say “it’s because sea water is more dense”, which it is, without explaining why that makes a difference. Nonetheless, the difference is marked and I don’t know why either.

  • 12. The water is always warmest at the surface.

This is a corollary of number ten in the previous list (water covered by ice is coldest). Water has a maximum density at 4 degrees Celsius. Therefore water at this temperature sinks to the bottom, and in the surface layer, the water temperature can be less or greater. As open water swimmers, we know that wind or boats can stir water, increasing the temperature in the surface layer by 1-2 degrees or sometimes dropping it. The reality is that surface sea water is usually a mix of perceptible temperatures whereas in lakes the coldest water is usually at the surface.

  • 13. Walruses and polar bears live in the Arctic.

Wherever there’s cold water, there are cold water swimmers. These are colloquially known as polar bears or walruses in different parts of the globe. Or just winter swimmers.

  • 14: Winter swimming in harder the further North one travels (aka Alaska, Siberia, Czech Republic).

Cold water is cold water. Water under a thick ice sheet in which people usually swim in holes, is typically about 4 degrees C. Air temperature plays a big factor, and some places with higher air temperature but also higher wind strengths (such as Ireland and the UK) and no ice cover, may be experientially just as cold (wind chill). Lough Dan for the 2013 Ice Mile where I completed my ice Mile was only 3.3 degrees. There was no snow or ice. The previous year was 1.3 degrees at the lake edge. What does change the further north one goes in certain areas is local cold water experience which is usually greater further north (or south in the southern hemisphere).

  • 15. Once you are used to really cold water there’s no danger.

This is one of the myths I have most difficulty with as it’s perpetuated by very experienced swimmers. There is always danger with cold water swimming. The danger is moderated by the person’s experience, but is not or never completely absent.

  • 16: Not everyone can do swim in cold water.

Mostly untrue. Most people, regardless of experience or body shape can do it, but there are contra-indications (people who shouldn’t for medical reasons). These include previous history or cardiac problem, some circulatory issues and other some other issues.

  • 17: “I just can’t handle the cold“.

Except for people with aforementioned and some other medical contra-indications, I don’t personally believe that most people are special with respect to cold. By definition, everyone can’t be special. Cold is an adverse condition for humans, getting used to it hurts everyone and takes everyone time. And also by definition human have in general undergone adaptations which allowed us to populate the temperature ranges of the earth.

  • 18. Cold water gives you a cold.

No. No, it really doesn’t. Not does getting caught in the rain. Blame your parents for this perpetuated nonsense. In fact as Point 6 in the first part illustrates, acclimatized swimmers are healthier with a boosted immune system. 100% of colds are caused by viruses.

  • After I abandoned my first Ice Mile attempt

    After I abandoned my first Ice Mile attempt

    19: You can swim in cold water as often as you like.

Russian and Czech cold water swimming experts, who have the longest experience with cold water swimming, say no more than one really cold swim per 24 hours, and preferably only every 2nd day. The Czech cold water swimming championships even preclude swimming more than once in 24 hours. What may be most important is the definition of cold and your experience. I don’t think I have ever done more than one swim in water of under ten degrees in one day, and certainly never under eight degrees.

  • 20. Men are better at cold than women.

In general terms the opposite is true for two reasons. Women are better at cold water because: 1); they have a more even distribution of sub-cutaneous body fat, and 2); women’s core temperature is 0.25 degrees Celsius higher than men. One effect of this is that women seem to feel cold more easily because their hands and feet get colder more easily. This makes many think they suffer worse from cold, but without the actual experience of cold water, they never learn the reality.


11 thoughts on “Ten More Common Myths of Cold Water Swimming

  1. I’m curious too about this once a day cold swim or every other day, being of Czech heritage. I can understand why if you’re only in the water for 20 minutes, how you could go in more than once a day without any negative consequences, indeed, why it might feel ‘warmer.’ But what if you’re swimming for an hour or more? Seems like once a day would be the max; but then what about the longer swims you talk about Donal of up to three hours in less than 10 C. I’m concerned about the Russians and Czechs who think it should only be every other day, and WHY? Since I am swimming in fresh water (about 11 C. I don’t have a thermometer, so have to go by nearby recorded points that may not reflect my actual swimming spot), for approximately an hour EVERY day, that’s okay right? You still get the health benefits right? Today, after two straight weeks of these swims, November 11, I felt the burning cold for the first time half way through, felt I was back in Northern Montana or Canada in glacial melt pools; but it’s okay, yes, the cold EFFECTS me, but it’s still awesome, addictive, exhilarating, and amazing. Thanks for your wonderful blog Donal.
    Gazelle in Oregon off the Pacific coast 🙂 Also any tips on getting a water thermometer? thanks! I don’t feel like this alone freak anymore swimming in November, thanks to your blog!! There are no polar bear clubs or organized cold swims near me! I’m truly a lone swimmer here too.


    • I’d lean toward what the Czechs say. Daily really cold water is a heavy burden on the body in recovery, in my opinion, and they have a lot of experience at it. They are also utterly dismissive of Ice Mile swimming, so I listen to them.

      I’ve stopped using thermometers, as I can guess the temp to within half a degree. The best best is a laboratory grade direct contact thermo or a high quality infrared thermo. Neither are cheap, at least in Europe, probably costing about €100, but they need an accuracy of less than one degree.


  2. “I don’t think I have ever done more than one swim in water of under ten degrees in one day, and certainly never under eight degrees.” – myself and other people I swim with have been known to “double dip” in winter. One January we did a dawn to dusk relay @ 7C were each of us swam for 10-20 minutes each hour for eight hours. We have noticed no especially adverse effects from multiple swims, apart from the accumulated tiredness. In fact we often say it feels warmer on the second, third etc. swim. 🙂


      • Wasn’t trying to get into a p*ssing contest on who’s tougher (hope it didn’t come across that way), especially not with the Irish crowd. You guys would win hands down.

        I just thought you might be interested to hear that the “Three Rivers” gang regularly double/triple dip in winter and we haven’t noticed any especially adverse effects of multiple swims in a single 24 hour period.

        I think we prefer this approach of multiple shorter swims to trying to organise a single (questionable) longer swim. It feels/seems safer and is also more inclusive as a lot of us find it more realistic to do 2-3 shorter swims then attempting the same combined time/distance in a single winter swim.

        Give it a go. 😉


    • Hey Harald, I did change the theme, but I have no control over the fonts. It’s possible the new theme uses a slightly smaller one, but I can’t change it. An easy fix though for any particular site though is usually to hold down the control key and spin the mouse wheel which increases or decreases font size in the browser without having to change settings, and you can revert just as easily afterwards.


  3. This is a great series! A further thought about Myth #11 (Fresh water feels colder than sea water at the same temperature)… Got an email from an old friend in Los Angeles recently. He lives near the beach and goes in the (sea) water every day, either surfing or swimming. He told me, “Our Pacific is still 70 degrees (21 C)… surfed bareback this morning and it’s mid-October!” — meaning that it’s very warm in the water for this time of year there, which I can confirm. When I asked him about this “ocean-pool temperature differential”, he said: “My guess is that one’s response to the temperature difference is probably more a result of our expectations… if one were in the tropics, one most certainly would say ‘why such freezing cold 70-degree ocean water?'” My friend may be right. Maybe it’s an Environmental Expectation thing.

    On the other hand, here’s an answer to this Googling question (“Is salt water warmer than fresh water?”) on answers.com (which is hardly a bonafide resource): “A 70 degree ocean will feel warm, but a 70 degree lap pool barely tolerable– too cold to swim in [Really? Ha!!!]. The reason has to do with the specific great [???] of water, which is influenced by saline. Heat loss from one’s body is more extensive and more rapid in fresh water than in salt water. The salt serves as an insulator, one might say. The perceptive difference is substantial– about 10 degrees. Therefore an 82 degree lap pool is analogous to a 72 degree ocean.” Could it be? Curious minds want to know.


    • I get where your mate is coming from, but I don’t think it’s that since many of the people who say are very experienced cold water swimmers. I would be able to categorise a 10 degree difference when the temp is already only 5 or 6 degrees. I think you’ve prompted to finally go back and try to find out an answer for this and thanks for the prompts and the ideas. The salt theory sounds interesting. Wouldn’t salt ions in water increase conductivity though?

      Leave it with me?


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